Ariel Space Mission

font size decrease font size increase font size
Print
Email

Write a comment

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was selected as the fourth medium-class mission in ESA's Cosmic Vision programme. It will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System.

It is the first mission dedicated to measuring the chemical composition and thermal structures of exoplanets, linking them to the host star's environment. This will fill a significant gap in our knowledge of how the planet's chemistry is linked to the environment where it formed, or whether the type of host star drives the physics and chemistry of the planet's evolution.

Observations of these worlds will give insights into the early stages of planetary and atmospheric formation, and their subsequent evolution, in the process also helping us to understand how our own Solar System fits into the bigger picture of the overall cosmos.

Ariel was selected in 2018 as the fourth medium-class science mission in ESA's Cosmic Vision plan. It was 'adopted' by ESA during the Agency's Science Programme Committee meeting on 12 November, paving the way towards construction.

"Ariel will enable planetary science far beyond the boundaries of our own Solar System," says Günther Hasinger, ESA's Director of Science. "The adoption of Ariel cements ESA's commitment to exoplanet research and will ensure European astronomers are at the forefront of this revolutionary field for the next decade and well beyond."

Ariel will be ESA's third dedicated exoplanet mission to launch within a ten-year period, with each mission tackling a unique aspect of exoplanet science. CHEOPS, the CHaracterising ExOPlanet Satellite, launched in December 2019, is already producing world-class science. PLATO, the PLAnetary Transits and Oscillations of stars mission, will be launched in the 2026 timeframe to find and study extrasolar planetary systems, with a special emphasis on rocky planets around Sun-like stars in the habitable zone – the distance from a star where liquid water can exist on a planet's surface. Ariel, planned to launch in 2029, will focus on warm and hot planets, ranging from super-Earths to gas giants orbiting close to their parent stars, taking advantage of their well-mixed atmospheres to decipher their bulk composition.

Exoplanet mission timeline. Credit: ESA

In the coming months, industry will be asked to make bids to supply spacecraft hardware for Ariel. Around summer next year, the prime industrial contractor will be selected to build it.

The mission's payload module, which includes a one metre-class cryogenic telescope and associated science instruments, is provided by the Ariel Mission Consortium. The consortium comprises more than 50 institutes from 17 European countries. NASA also contributes to the payload.

"After an intensive period working on the preliminary design concepts and on the consolidation of the required technologies to demonstrate the mission feasibility, we are ready to move Ariel forward to the implementation stage," says ESA's Ariel study manager Ludovic Puig.

The telescope's spectrometers will measure the chemical fingerprints of a planet as it crosses in front of – 'transits' – its host star, or passes behind it – an 'occultation'. The measurements will also enable astronomers to observe the dimming of the host star by the planet with a precision of 10–100 parts per million relative to the star.

Ariel will be able to detect signs of well-known ingredients in the planets' atmospheres such as water vapour, carbon dioxide and methane. It will also detect more exotic metallic compounds to decipher the overall chemical environment of the distant solar system. For a select number of planets, Ariel will also perform a deep survey of their cloud systems and study seasonal and daily atmospheric variations.

"With Ariel we will take exoplanet characterisation to the next level by studying these distant worlds both as individuals and, importantly, as populations, in much greater detail than ever before possible," says ESA's Ariel study scientist Göran Pilbratt.

"Our chemical census of hundreds of solar systems will help us understand each planet in context of the chemical environment and composition of the host star, in turn helping us to better understand our own cosmic neighbourhood," adds ESA's Ariel project scientist Theresa Lueftinger.

"We're pleased to enter the implementation phase of the Ariel mission," says ESA's Ariel project manager Jean-Christophe Salvignol. "We're moving towards the optimal spacecraft design for answering fundamental questions about our place in the cosmos."

Ariel is planned for launch on ESA's new Ariane 6 rocket from Europe's spaceport in Kourou, French Guiana. It will operate from an orbit around the second Sun-Earth Lagrange point, L2, 1.5 million kilometres directly 'behind' Earth as viewed from the Sun, on an initial four-year mission. The ESA-led Comet Interceptor mission will share the ride into space.

SUMMARY

Ariel Atmospheric Remote-sensing Infrared Exoplanet Large-survey Enabling Planetary Science across Light-years
Cosmic Vision Themes	What are the conditions for planet formation and the emergence of life?
Key Science Questions	What are exoplanets made of? How do planets and planetary systems form? How do planets and their atmospheres evolve over time?
Primary goal	To perform a large-scale survey of a statistically well defined, diverse sample of about 1000 exoplanets, ranging from gas giants to rocky planets and preferentially in the hot to temperate zones of F- to M-type stars, and compile a catalogue of planetary compositions and properties
Wavelengths	Visible and infrared photometry: 0.50-0.55 µm, 0.8-1.0 µm, 1.0-1.2 µm Infrared spectroscopy: two medium-resolution channels (1.95-3.9 µm and 3.9-7.8 µm) and one low-resolution channel (1.25-1.95 µm)
Payload	An off-axis Cassegrain telescope (elliptical primary mirror of 1.1m x 0.7m, effective collecting area 0.64 m²), diffraction limited at 3 μm Ariel medium-resolution InfraRed Spectrometer (AIRS) covering the 1.95 – 7.80 μm wavelength range A Fine Guidance System (FGS) module with three narrow-band visible to near-infrared photometer channels (two used as guidance sensors as well as for science) and a low-resolution near-infrared spectrometer
Orbit	An eclipse-free (Earth-Moon) large amplitude halo orbit around the Sun-Earth L2 point
Lifetime	Nominal 4-year operational timeline, with a potential extended science operations phase lasting for two further years
Launch	Ariel is foreseen to launch in 2029
Type	Medium (M-class) mission

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, will study how planets and planetary systems form and evolve by surveying a large, diverse sample of approximately 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. In March 2018, Ariel was selected as M4, the fourth medium-sized (M-class) mission in ESA’s Cosmic Vision Plan.

Ariel will address one of the key questions within ESA's 2015-2025 Cosmic Vision Plan: What are the conditions for planet formation and the emergence of life?

Despite the large numbers of different exoplanets that have been discovered to date, there is still no clear link between the presence, size, or orbital parameters of a planet and the nature of its parent star. To understand more about exoplanets and exoplanetary systems, an unbiased large-scale survey of exoplanets is required — to perform such a survey is Ariel's key observational objective.

Ariel will study the nature of the exoplanets themselves, both as individuals and as populations, and monitor their host stars for stellar activity. Using both transit and eclipse spectroscopy (in near infrared wavelengths) and photometry (in visible wavelengths), Ariel will explore the properties and atmospheres of approximately 1000 transiting planets, including preferentially warm and hot gas giants, Neptunes, super-Earths, and Earth-sized planets, and seek to understand what planets are made of and how planetary systems form and evolve.

SCIENCE OBJECTIVES

Although astronomers have discovered large numbers of exoplanets in recent years, it is still far from clear what the nature of these planets are, how they formed and how they evolve. To make progress, the study of exoplanets must shift from 'discovery' towards 'studying and understanding' — as a starting point astronomers and planetary scientists need a simple taxonomy of planets and planetary systems. For this, a dedicated survey of a statistically well-defined, large and diverse sample of exoplanets is needed, with simultaneous observations gathered across a consistent wavelength range, in order to understand exoplanets both as individuals and as populations.

Towards a taxonomy for planets

Ariel is a dedicated survey mission capable of observing a large, diverse and well-defined sample of exoplanets around a range of stellar types. It is designed to perform high-accuracy transit, eclipse, and phase-curve observations employing simultaneous multiband photometry in visible wavelengths and spectroscopy in near infrared wavelengths. Its payload comprises a 1-metre class, three-mirror telescope, an infrared spectrometer, and a Fine Guidance System module providing three narrow-band photometry channels (two used as guidance sensors as well as for science) and a low-resolution near-infrared spectrometer.

Key science questions:

What are exoplanets made of?
How do planets and planetary systems form?
How do planets and their atmospheres evolve over time?

Key science objectives:

Detect planetary atmospheres, and identify their composition and structure
Determine vertical and horizontal temperature structure, and diurnal and seasonal variations
Identify chemical processes at work (thermochemistry, photochemistry, transport quenching)
Constrain planetary interiors (breaking the radius-mass degeneracy)
Quantify the energy budget (albedo, temperature)
Constrain formation and evolution models (evidence for migration)
Detect secondary atmospheres around terrestrial planets (evolution)
Investigate the impact of stellar and planetary environment on exoplanet properties

Ariel will observe and study approximately 1000 preferentially warm and hot transiting gas giants, Neptunes, and super-Earths around a range of star types.

The planets targeted will preferentially be warm and hot (> 600 K) to ensure that their atmospheres are well-mixed and subject to minimal condensation and sequestration, allowing an accurate study of their bulk and elemental composition (from e.g. water (H₂O), carbon dioxide (CO₂), methane (CH₄), ammonia (NH₃), hydrogen cyanide (HCN), and hydrogen sulphide (H₂S) through to more exotic metallic compounds, such as titanium oxide (TiO) and vanadium oxide (VO), and condensed species). Observations of these hot exoplanets will provide insight into the early stages of planetary and atmospheric formation during the nebular phase and the following few million years.

Transit and eclipse spectroscopy methods, whereby the signals from the star and planet are differentiated using knowledge of the planetary ephemerides, will allow Ariel to measure atmospheric signals from the planets at levels of at least 10^-4 relative to the star and, given the bright nature of targets, allow more sophisticated techniques — such as phase-curve analysis and eclipse mapping — that give a deeper insight into the nature of the atmospheres.

Ariel will deliver an in-depth catalogue of planetary spectra, characterising molecular abundances, chemical gradients, atmospheric structure, diurnal and seasonal variations, clouds, and albedo measurements. The mission will thus provide a truly representative picture of the chemical nature of the exoplanets studied, and relate this directly to the type and chemical environment of their host stars.

Ariel is complementary to several other exoplanet missions; potential targets will be identified and studied by a number of important missions in the next decade, including ESA's CHEOPS, Gaia, and PLATO missions, NASA's TESS survey mission, and the NASA/ESA/CSA James Webb Space Telescope. However, Ariel is the only mission designed for and dedicated to performing a spectroscopic survey of a large, well defined sample of exoplanets.

SPACECRAFT

Ariel's design builds on the thermal design heritage from ESA's Planck mission, and is a modified version of that proposed for EChO (the Exoplanet Characterization Observatory), a previous Cosmic Vision candidate that was considered for the M3 launch opportunity in 2024 (for which the planet-hunting PLATO mission [PLAnetary Transits and Oscillations of stars] was ultimately selected).

The design has been simplified, and its mass reduced, to meet programmatic constraints — unlike EChO, which also targeted temperate exoplanets, Ariel will preferentially focus on warm and hot ones, thus requiring a simpler payload. The launch mass of the entire spacecraft is approximately 1300 kg.

The spacecraft is designed with two distinct modules: the Service Module (SVM) and Payload Module (PLM). These two modules are thermally isolated from one another — the SVM sits at the 'bottom' of the spacecraft. Three V-Grooves, composed of an Aluminium-skin/Aluminium-honeycomb sandwich, and three pairs of low conductivity Glass Fiber Reinforced Plastic (GFRP) bipod struts sit on top of the SVM to support the PLM (including the optical bench, the telescope and the instruments). This thermal shield assembly allows the complete PLM to be passively cooled to ~55K (optical bench, telescope and instruments). In addition, a Neon Joule-Thomson cooler allows the AIRS long wavelength channel to be cooled to ~42K.

The PLM comprises an off-axis Cassegrain telescope (with a primary mirror of approximately 1.1 m × 0.7 m) with a third beam collimating mirror, the Ariel infrared spectrometer (AIRS) covering the 1.95 – 7.80 μm wavelength range, and a Fine Guidance System (FGS) module with three narrow-band visible to near-infrared photometer channels (two used as guidance sensors as well as for science) and a low-resolution near-infrared spectrometer.

The structure of the PLM is based on a horizontal telescope configuration. The complete optical bench and all mirrors will be made out of Aluminium.

The propellant tank is accommodated inside the SVM, while the solar panels, thrusters and high gain antenna are accommodated underneath. Ariel will use a hydrazine monopropulsion system. Ariel's Attitude and Orbital Control Systems (AOCS) will be three-axis stabilised and wheel-based, operating the wheels in a narrow angular speed range, away from any peak vibration mode and away from any possible amplification frequency of the spacecraft structure to mitigate the impact of micro-vibrations on the pointing budgets.

PAYLOAD

The Ariel payload consists of an integrated suite comprising the telescope assembly (TA), the Ariel infrared spectrometer (AIRS), and the Fine Guidance System (FGS)/photometer module, along with the necessary supporting hardware and services. All these units are accommodated inside the cryogenic payload module, while warm payload units are accommodated inside the service module (the FGS Control Unit, the Instrument Control Unit, and the cryo-cooler and Cooler Drive Electronics).

TA — TELESCOPE ASSEMBLY

The TA is an off-axis Cassegrain telescope followed by a third parabolic mirror to recollimate the beam, passively cooled to a temperature of ~55 K. It has an elliptical main mirror with dimensions of 1.1 m × 0.7 m — equivalent to 0.9 m circular — a diffraction limit of about 3 µm, and a focal ratio (f) of 13.4.

AIRS — ARIEL IR SPECTROMETER

AIRS is a broad-band, medium-resolution near-infrared spectrometer operating between 1.95 µm and 7.8 µm. The spectrometer is a single module incorporating two dual Offner channels covering the 1.95–3.9 µm and 3.9–7.8 µm wavelength bands, and provides a resolving power of R~30–200 across its spectral range. The proposed detector is a fine-tuned version of the Teledyne MCT (Mercury-Cadmium-Telluride) array developed for NEOCam (the Near-Earth Object Camera). The operating temperature for the detectors is below 42 K, AIRS is mounted on the optical bench alongside the FGS and telescope interface.

FGS (FINE GUIDANCE SYSTEM) MODULE & NEAR-INFRARED PHOTOMETER

The FGS module provides three narrow-band visible to near-infrared photometer channels (two used as guidance sensors as well as for science) and a low-resolution near-infrared spectrometer. The four-channel FGS/photometer will include a Gregorian telescope, and covers three narrow spectral bands spanning 0.50–0.55 µm, 0.8–1.0 µm and 1.0–1.2 µm, and a low-resolution 1.25–1.95 µm spectrometer. Both the FGS and NIR-photometer are mounted on the optical bench.

OPERATIONS

Ariel is the fourth medium-class (M4) mission in ESA's Cosmic Vision Plan. It is scheduled for launch in 2029.

LAUNCH AND ORBIT

Ariel will be launched into an (Earth-Moon) eclipse-free orbit around the Sun-Earth L2 point. It will be a large amplitude quasi-halo orbit, as was the case for ESA's Herschel Space Observatory, where the angle between the Sun, Spacecraft, and Earth can be ≥ 30 degrees. From Ariel's planned orbit, the complete sky is accessible within 3 months, with a source at the ecliptic observable for at least 30% of the mission lifetime.

The proposed launch vehicle is an Ariane 62, a modular launcher with two P120 solid-propellant boosters.

The Launch and Early Operations phase will cover the time until the first Transfer Correction Manoeuvre is executed (within 2 days after launch). It will then take Ariel up to six months to reach operational orbit, go through spacecraft commissioning and science demonstration phases. Once in its final configuration, Ariel will perform one manoeuvre per month to maintain its orbit.

OPERATIONS

Ariel has a nominal 4-year operational timeline, consisting of 6 months of launch and early operations, commissioning, performance verification, and science demonstration phases, followed by a 3.5 year duration routine science operations phase, with a potential extended science operations phase lasting for two further years.

A payload consortium funded by national agencies will provide the full Ariel payload (the complete payload module, including telescope and instruments, and the warm payload units) and will have significant involvement in the science ground segment, while ESA will provide the service module, the integration and testing of the spacecraft flight model, as well as being responsible for the launch and operations.

The ground segment responsibility and implementation will be split between ESA and a nationally-funded Instrument Operations and Science Data Centre (IOSDC) payload consortium. Ariel data products will be distributed to the scientific community through an ESA-provided science archive.

ESA will provide:

A Mission Operations Centre (MOC) located at the European Space Operations Centre (ESOC) in Darmstadt, Germany
A Science Operations Centre (SOC) located at the European Space Astronomy Centre (ESAC), in Madrid, Spain
ESA tracking station network (ground stations)

PUBLICATIONS

ARIEL DEFINITION STUDY REPORT:
November 2020

ARIEL ASSESSMENT STUDY REPORT:
March 2017

ARIEL YELLOW BOOK TECHNICAL NOTES:
Link to all Technical Notes

ARIEL SCIENTIFIC PROPOSAL & OUTCOME OF ESA CDF STUDY:
Link to ESA website

Ariel Special Issue in Experimental Astronomy: coming soon!

Barnes, J.R. et al. Exoplanet mass estimation for a sample of targets for the Ariel mission;

Barstow, J. et al. A retrieval challenge exercise for the Ariel mission;

Brucalassi, A. et al. Determination of stellar parameters for Ariel targets: a comparison analysis between different spectroscopic methods;

Caines, H. et al. Simulation of Ephemeris Maintenance of Transiting Exoplanets’

Changeat et al. Disentangling Atmospheric Compositions of K2-18 b with Next Generation Facilities;

Charnay, B. et al. A survey of exoplanet phase curves with Ariel;

Chioetto, P . et al. Qualification of the thermal stabilization, polishing and coating procedures for the aluminum telescope mirrors of the Ariel mission;

Danielski, C. et al. The homogeneous characterisation of Ariel host stars;

Demangeon, O. et al. Need, Scale and Feasibility of an Ariel radial velocity campaign;

Encrenaz, T. et al. Observability of temperate exoplanets with Ariel;

Ferus M. et al. Ariel – a window to the origin of life on early Earth?

Focardi, M. et al. The Ariel Instrument Control Unit its role within the Payload and B1 Phase design;

Garai, Z. et al. Grazing, non-transiting disintegrating exoplanets observed with the planned Ariel space observatory A case study using Kepler-1520b;

Garcia Perez, A. et al. Thermoelastic evaluation of the Payload Module of the Ariel mission;
Guilluy, G. et al. On The Synergy Between Ariel and Ground-Based High-Resolution Spectroscopy;

Haswell, C. A. Extended Use of the Ariel Core Survey Data;

Helled, R. et al. Ariel Planetary Interiors White Paper; Ito, Y. et al. Detectability of mineral atmospheres with Ariel;

Kiss, C. et al. Ancillary science with Ariel: Feasibility and scientific potential of young star observations;

Kokori A. et al. ExoClock Project: An open platform for monitoring the ephemerides of Ariel targets with contributions from the public;

Morales, J.C. et al. Ariel scheduling using Artificial Intelligence;

Morello, G. et al. The Ariel 0.6 – 7.8 μm stellar limb- darkening coefficients;

Morgante, G. et al. The thermal architecture of the ESA Ariel payload at the end of Phase B1;

Moses, J.I. et al. Chemical variation with altitude and longitude on exo-Neptunes: Predictions for Ariel phase- curve observations;

Pearson C. et al. The Ariel Ground Segment and Instrument Operations Science Data Centre;

Seli, B. et al. Stellar flares with Ariel;

Szabó, G. et al. High-precision photometry with Ariel;

Turrini, D. et al. Exploring the link between star and planetary formation with Ariel;

Wolkenberg, P. et al. Effect of clouds on emission spectra for Super Venus within Ariel;

Peer reviewed publications about Ariel

Mugnai, L. V.; Pascale, E.; Edwards, B.; Papageorgiou, A.; Sarkar, S. (2020); ArielRad: the Ariel radiometric model; Experimental Astronomy, Volume 50, Issue 2-3, p.303-328

Sarkar S., E. Pascale, A. Papageorgiou, L. Johnson, I. Waldmann, ExoSim: the Exoplanet Observation Simulator, Experimental Astronomy, 2020, arXiv:2002.03739.

Nikolaou N. et al. Lessons Learned from the 1st ARIEL Machine Learning Challenge: Correcting Transiting Exoplanet Light Curves for Stellar Spots , AJ, 2020.

Bourgalais, J., Carrasco, N., Changeat, Q., Venot, O., Jovanović, L., Pernot, P., Tennyson, J., Chubb, Katy L., Yurchenko, Sergey N., & Tinetti, G. (2020), Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments. The Astrophysical Journal, Volume 895, Issue 2, id.77.

Pluriel, W.; et al. (2020), ARES. III. Unveiling the Two Faces of KELT-7 b with HST WFC3 , The Astronomical Journal, 160, 112

Skaf N. et al., (2020) ARES II: Characterising the Hot Jupiters WASP-127 b, WASP-79 b and WASP-62 b with HST, AJ, 160, 109.

Edwards B. N. et al. (2020), ARES I: WASP-76 b, A Tale of Two HST Spectra, Accepted for publication in AJ, arXiv:2005.02374.

Min, M.; Ormel, C. W.; Chubb, K.; Helling, C.; Kawashima, Y. (2020); The ARCiS framework for exoplanet atmospheres. Modelling philosophy and retrieval; Astronomy & Astrophysics, Volume 642, id.A28, 35.

D. Turrini, A. Zinzi and J. A. Belinchon (2020) Normalized angular momentum deficit: A tool for comparing the violence of the dynamical histories of planetary systems, A&A, 636, A53.

Changeat, Q., Edwards, B., Al-Refaie, A., F., Tsiaras, A., Waldmann, I. P., Tinetti, G., Disentangling Atmospheric Compositions of K2-18 b with Next Generation Facilities. Submitted ApJ, arXiv:2003.01486.

Petralia, A., Micela, G., (2020) Principal Component Analysis to correct data systematics. Case study: K2 light curves, Experimental Astronomy, 49, 97.

Barstow J. K., Q. Changeat, R. Garland, M. R Line, M. Rocchetto, I. P Waldmann (2020), A comparison of exoplanet spectroscopic retrieval tools, Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 4, p.4884-4909.

Changeat Q., Al-Refaie A., Mugnai L.V., Edwards B., Waldmann I. P., Pascale E., Tinetti G. (2020), Alfnoor: A Retrieval Simulation of the Ariel Target List, The Astronomical Journal, 160, 80, 2020.

Changeat Q., Keyte L., Waldmann I. P., Tinetti G. (2020), Impact of planetary mass uncertainties on exoplanet atmospheric retrievals, The Astrophysical Journal, 896, 107, 2020.

Changeat Q., B. Edwards, I. P. Waldmann, and G. Tinetti, Toward a More Complex Description of Chemical Profiles in Exoplanet Retrievals: A Two-layer Parameterization, The Astrophysical Journal, 886 39, 2019.

Edwards, B. N.; L. Mugnai, G. Tinetti, E. Pascale, and S. Sarkar (2019) An Updated Study of Potential Targets for Ariel, AJ, 157 242.

Middleton K. F. et al., An integrated payload design for the atmospheric remote-sensing infrared exoplanet large-survey (ARIEL): results from phase A and forward look to phase B1, 2019, Proceedings of the SPIE, Volume 11180, id. 1118036, 7 pp.

Sarkar, S. et al., Stellar pulsation and granulation as noise sources in exoplanet transit spectroscopy in the ARIEL space mission, Monthly Notices of the Royal Astronomical Society, 481, 3, p. 2871-2877, 2018.

Tinetti, G., Drossart, P., Eccleston, P. et al., A chemical survey of exoplanets with ARIEL, Exp Astron (2018) 46: 135. https://doi.org/10.1007/s10686-018-9598-x

Venot, O., Drummond, B., Miguel, Y. et al., A better characterization of the chemical composition of exoplanets atmospheres with ARIEL, Exp Astron (2018) 46: 101. https://doi.org/10.1007/s10686-018-9597-y

Zingales, T., Tinetti, G., Pillitteri, I. et al., The ARIEL mission reference sample, Exp Astron (2018) 46: 67. https://doi.org/10.1007/s10686-018-9572-7

Turrini, D., Miguel, Y., Zingales, T. et al., The contribution of the ARIEL space mission to the study of planetary formation, Exp Astron (2018) 46: 45. https://doi.org/10.1007/s10686-017-9570-1

Encrenaz, T., Tinetti, G. & Coustenis, A., Transit spectroscopy of temperate Jupiters with ARIEL: a feasibility study, Exp Astron (2018) 46:31.https://doi.org/10.1007/s10686-017-9561-2

Puig, L., Pilbratt, G., Heske, A. et al., The Phase A study of the ESA M4 mission candidate ARIEL, Exp Astron (2018) 46: 211. https://doi.org/10.1007/s10686-018-9604-3

Focardi, M., Pace, E., Farina, M. et al., The ARIEL Instrument Control Unit design, Exp Astron (2018) 46: 1. https://doi.org/10.1007/s10686-017-9560-3